CTCF and SMC1 co-localize to nuclear foci and form complexes.

A). Immunofluorescence analysis of CIN 612 cells following calcium induced differentiation for 72 hours. pSMC1 signal is in green, while CTCF proteins are shown in red. The merge is yellow and shows that most CTCF and pSMC1 proteins co-localize in distinct nuclear foci. Numerous CTCF foci are detected in the nuclei of HPV positive cells but only a subset co-localize with pSMC1 while all pSMC1 foci co-localize with CTCF. B).Proximity-ligation assays (on-slide co immunoprecipitation) of pSMC1 and CTCF show complex formation in nuclear foci. C). Quantitation of pSMC1 and CTCF foci in HFK and CIN 612 cells. Foci in 183 HFKs and 107 CIN612 cells from three individual experiments were counted. Interactions of CTCF with pSMC1 in HPV positive cells is statistically significant as indicated by the students t-test, p≤.0001.